SKGF_Advisory_Consider a Prosecution History Disclaimer for Every Continuation Application_2007
Consider a Prosecution
History Disclaimer for Every
Michael V. Messinger & Jon E. Wright
Consider a Prosecution History Disclaimer
for Every Continuation Application
Michael V. Messinger and Jon E. Wright
Patent owners and practitioners should consider modifying their continuation practice in
light of a recent case from the Federal Circuit. In Hakim v. Canon Avent Group, the court
appeared to lay down strict requirements for practitioners using continuation applications to
broaden unnecessarily narrow claims and clarify unnecessary estoppels created during
prosecution of parent applications. In Hakim, the court relied on statements made during
prosecution of a parent application to narrowly construe a claim term that was explicitly
broadened in the child application. The court ruled that the applicant's efforts to disclaim the
perceived estoppel were insufficient.
In a case involving quot;sippy-cupquot; valves, patent owner Hakim argued around asserted prior
art references by pointing to two separate mechanisms used to prevent leakage. The first
mechanism was a flexible valve material having a quot;slitquot; therein that responds to suction. The
second mechanism was a quot;blocking elementquot; against which the quot;slitquot; rested when in a relaxed
position. Hakim stated that quot;[n]one of the references cited in the Office Action … teach or
suggest such a no-spill mechanism having a slit sitting against a blocking element such as recited
in all of the pending claims.quot; The Examiner allowed the pending claims.
Believing that the term quot;slitquot; was too narrow, Hakim filed a continued prosecution
application, or a CPA. The CPA was accompanied by an attorney letter stating that Hakim was
broadening claims 1 and 2, and an amendment changing quot;slitquot; to quot;opening.quot; The continuation
claims were allowed with no further comment or rejection by the examiner, and issued in U.S.
Patent No. 6,321,931 (quot;the '931 patentquot;).
Hakim sued Cannon Avent Group (quot;Aventquot;) alleging that its sippy-cup valves infringed
Hakim's '931 patent. The Avent valves had a hole in the flexible valve material, instead of a slit.
A key issue became how to construe the term quot;openingquot; in the '931 patent. Despite the Hakim's
attempt to broaden the claims in the continuation application, the district court narrowly
construed the '931 claims to a sealing mechanism that includes a flexible valve material or
diaphragm having a slit. The district court stated: quot;Because Hakim did not retract any of his
arguments distinguishing the prior art, he is held to the restrictive claim construction he argued
during prosecution of the patent.quot; The court thus ruled on summary judgment that Avent's
devices did not infringe.
On appeal to the Federal Circuit, Hakim argued that the district court improperly relied
on the arguments he made during prosecution of the abandoned parent application. According to
Hakim, he avoided any perceived estoppels that may have crept into his claims by re-filing his
application with the broader claims, and explicitly flagging the change to assist the examiner.
Avent, on the other hand, argued that the totality of the prosecution history nonetheless limits
Hakim to the embodiment with the slit. Avent stressed that quot;when Hakim wrote to the examiner
that he was broadening the claims, he did not specifically point out that he no longer intended to
be limited to the specific mechanism that he had previously argued was the distinguishing feature
of his invention.quot; (Slip op. at 5-6.)
In a unanimous decision, the Federal Circuit panel affirmed the district court ruling. The
court acknowledged that Hakim quot;had the right to refile the application and attempt to broaden the
claims.quot; (Slip op. at 6.) However, the court also stressed the well known doctrine of prosecution
history estoppel, noting that quot;an applicant cannot recapture claim scope that was surrendered or
disclaimed.quot; Relying on the public notice function of the patent and prosecution history, the
court stated: quot;Although a disclaimer made during prosecution can be rescinded, permitting
recapture of the disclaimed scope, the prosecution history must be sufficiently clear to inform the
examiner that the previous disclaimer, and the prior art that it was made to avoid, may need to be
It is well settled that the prosecution history of related cases is relevant intrinsic evidence
that may be considered during claim construction. With this ruling, however, the Federal Circuit
made it clear that simply filing a continuation application with broader claims is not sufficient to
overcome or disclaim arguments made over the narrower claims during prosecution of the
parent. This is true even where the applicant explicitly advises the examiner that the
continuation claims are broader than those in the parent. To pursue broader claims than argued
previously, an applicant may now have to make an explicit disclaimer by informing the examiner
of pertinent art cited in the parent application, and arguments made to avoid it.
In view of Hakim, the authors suggest patent owners and practitioners reconsider their
current continuation application practice. This is especially true where continuations are filed to
broaden unnecessarily narrow claims or to clarify unnecessary estoppels that may have crept in
during prosecution of the parent. One solution may be to include a blanket disclaimer such as
The claims in the instant application are different than those of the parent
application or other related applications. The Applicant therefore
rescinds any disclaimer of claim scope made in the parent application or
any predecessor application in relation to the instant application. The
Examiner is therefore advised that any such previous disclaimer and the
cited references that it was made to avoid, may need to be revisited.
Further, the Examiner is also reminded that any disclaimer made in the
instant application should not be read into or against the parent
In sum, any continuation application should be evaluated with the lessons of Hakim in
mind. Whether using a blanket disclaimer, or something more specific, applicants should
explicitly and directly disclaim previous statements that could unnecessarily carry forward and
contaminate continuation claims. Existing patents issued from continuation applications may
also need to be reviewed with care where continuation disclaimers are absent.
Such continuation disclaimers are a new animal. Time will tell whether they will be
effective. Hakim, if read broadly, may be a new hurdle to filing successive continuations in U.S.
patent practice. On the other hand, practioners may be able to harness continuation disclaimers
to keep the door open for continuation practice and clearly overcome prior estoppels.
This article reflects the present thoughts of the authors, and should not be attributed to any of Sterne, Kessler,
Goldstein & Fox P.L.L.C. former, current, or future clients. The content is for purposes of discussion and should not
be considered legal advice. Copyright 2007 Sterne Kessler.
Sterne, Kessler, Goldstein & Fox P.L.L.C. 1100 New York Avenue, NW Washington, DC 20005 www.skgf.com